The present invention relates to an internal combustion engine with preferably two exhaust gas turbcchargers consisting each of a turbine and of a compressor driven by the turbine, whose compressors are connected by way of separate charging pressure lines to a common suction manifold and whose turbines are connected into separate exhaust gas lines starting from an exhaust gas manifold, in which one exhaust gas turbocharger is adapted to be connected-in in addition to the other exhaust gas turbocharger during the operation of the internal combustion engine, and in which a controllable blow-off valve (waste gate) is connected into a by-pass line starting from the exhaust gas manifold and by-passing the turbines of both exhaust gas turbochargers and a controllable switch-in valve is connected into the exhaust gas line of the turbine of the exhaust gas turbocharger adapted to be connected-in.
By equipping internal combustion engines with exhaust gas turbochargers, it is possible to regain at least a part of the energy loss present in the exhaust gases and to conduct it again back to the internal combustion engine. Conditioned by the manner of operation of the exhaust gas turbochargers, to supply significant charging pressures only with a large exhaust gas stream, the disadvantage results, especially for the strongly non-steadily operated vehicle engines, of inadequate power output and lacking torque in the lower rotational speed, respectively, load range.
It has therefore already been proposed to equip the internal combustion engine with two exhaust gas turbochargers whereby one is specifically designed for the lower load range of the internal combustion engine, and the second exhaust gas turbocharger is additionally switched-in or connected-in in addition to the first turbocharger in order to cover the full load range of the internal combustion engine. A supercharging system is created with such a system, as is described, for example, in the DE-OS No. 34 20 015 and corresponding U.S. Pat. No. 4,709,552, which produces a noticeable torque and power output increase of the internal combustion engine already at low rotational speeds and is effective over the entire rotational speed range without significant power output collapse.
It is the object of the present invention to further optimize this supercharging system by a deliberate electronic regulation, respectively, control, to further reduce the power output and torque collapses in the transition areas between the differing load conditions and to protect the internal combustion engine and exhaust gas turbochargers effectively against overloads.
The underlying problems are solved according to the present invention in that the activation of the blow-off valve and of the switch-in valve is subjected to an anticipatory control dependent on condition magnitudes (parameters) on which is superimposed at least one regulation dependent on the suction pipe pressure.
The advantages of the present invention reside in the first instance in that the charging system according to the DE-OS No. 34 20 015 and corresponding U.S. Pat. No. 4,709,552, is further optimized by a deliberate electronic regulation, respectively, control matched to the differing operating conditions of the internal combustion engine inclusive the supercharging system and a collapse in the power output, respectively, torque behavior of the overall system is practically no longer noticeable.
The thus-supercharged internal combustion engine exhibits an overall behavior which corresponds to an internal combustion engine of significantly larger volume with larger number of cylinders. Therebeyond, it is achieved that the internal combustion engine and the supercharging system are reliably protected against overload/damage.